With the introduction of concept of the provider-level Ethernet, for enabling the Ethernet to meet the telecommunication-level standard, a higher requirement for protection and switching of the Ethernet is raised. In existing protection and switching technology supporting the Provider Backbone Bridge Traffic Engineering (PBB-TE) technology, the protection of Traffic Engineering Service Instance (TESI) is supported at present. That is an end-to-end tunnel protection. However, the end-to-end protection scheme not only requires longer time of protection and switching, but also involves too many nodes, which makes it impossible to implement protection of intermediate link and node. Thus, the PBB-TE segment protection is introduced. A protection segment is specially configured in a working segment of the PBB-TE tunnel to protect it. The working segment and the protection segment compose an Infrastructure Protection Group (IPG).
As shown in FIG. 1, there is one working segment and one or multiple protection segments in a protection group. In normal conditions, when there is no fault detected on the working segment, all traffics protected by the PBB-TE segment protection group are forwarded from the working segment. But, once there is fault occurring on the working segment, if Segment Edge Bridge (SEB) of the PBB-TE segment protection group, i.e., SEB1 and SEB2 shown in FIG. 1, can detect the fault in time, then the SEB will trigger update of a forwarding table. And the SEB will modify the egress port of the forwarding table corresponding to the TESI protected by the protection domain IPG, into the egress port corresponding to the protection segment on the SEB. Thereby, the traffic is switched to the protection segment, protection of the working segment is implemented, normal forwarding of network traffic is ensured, and network reliability is improved. The SEB described here can be either Backbone Edge Bridge (BEB) on the PBB-TE tunnel or Backbone Core Bridge (BCB) on the PBB-TE tunnel. The protection and switching technology has been established as a project in the IEEE standards organization, and the project number is 802.1Qbf. The project supports the PBB-TE segment protection of 1:1 as well as the PBB-TE segment protection of M:1, that is, a PBB-TE segment protection group of M:1 is composed of one working segment and M protection segments, wherein M is more than 1 and the working segment is protected by the M protection segments. The existing protection and switching technology can greatly improve system reliability.
FIG. 2 shows a diagram of PBB-TE segment and its fault detecting mechanism. In FIG. 2, both of the two endpoints SEB1 and SEB2 of the segment can specifically be the BEB or the BCB, and a Segment Intermediate Bridge (SIB) can specifically be BCB. All of Segment Endpoint Port (SEP) 1 on the SEB1, SEP2 on the SEB2, and Provider Network Port (PNP) including the SEP1 and the SEP2 are represented by ; and  represents a Segment Intermediate Port (SIP).
The names involved in the related art are described below.
The member segment means the working segment or the protection segment of a protection group.
The working segment means the segment that traffic passes through in normal operation, as shown in FIG. 5.
The protection segment means the segment that bears the traffic after fault occurring on the working segment is detected or after a management command of switching is received and switching is performed, as shown in FIG. 5.
The segment means it is composed of a series of PNPs, and LAN and MAC relays among the PNPs, as shown in FIG. 5.
The SEB means two endpoints for ending segment, and the SEB can be either BEB device in the PBB-TE network or BCB device, as shown in FIG. 5. The bridge device in middle of a segment is SIB.
In FIG. 5,  represents SEP,  represents SIP, and both the SEP and the SIP are PNP;  represents the working segment;  represents the protection segment;  represents bridge;  represents the TESI; two endpoints SEB of a segment can specifically be the BEB or the BCB; and the bridge device SIB can specifically be BCB.
The IPG traffic switching means that: if a previous group of TESI traffic protected by the IPG passes through the working segment, when performing the IPG traffic switching, the previous TESI traffic passing through the working segment is redirected to pass through the protection segment; or, if a previous group of TESI traffic protected by the IPG passes through the protection segment, when performing the IPG traffic switching, the previous TESI traffic passing through the protection segment is redirected to pass through the working segment. The redirecting described here is usually implemented by modifying the egress port of the items in the forwarding table corresponding to the TESI.
However, in many cases, it is not realistic to configure multiple protection segments for any one working segment for protection, for it may be limited by conditions, such as network resource. If it may be considered to protect a particularly important part of the path and protection for the key protected path is implemented through the protection group overlay, then effects of saving network resource and increasing the utilization rate of network resource can be achieved. But there is no implementation that can achieves these effects at present.